:root {
  --bg:        #f5f4f0;
  --surface:   #ffffff;
  --border:    #e2e0d8;
  --border-md: #ccc9be;
  --text:      #1a1917;
  --muted:     #6b6860;
  --hint:      #9b9890;
  --green:     #1a7a52;
  --green-bg:  #eaf5f0;
  --blue:      #1755a8;
  --blue-bg:   #eaf0fb;
  --amber:     #8a5d0a;
  --amber-bg:  #fdf3dd;
  --code-bg:   #f0ede6;
  --tag-linux:   #eaf5f0; --tag-linux-t:   #0f6e56;
  --tag-docker:  #e6f0fb; --tag-docker-t:  #0b3a7a;
  --tag-web:     #fceae7; --tag-web-t:     #8a2a1a;
  --tag-git:     #eeedfe; --tag-git-t:     #4a3fb0;
  --tag-monitor: #fdf3dd; --tag-monitor-t: #8a5d0a;
  --radius:    10px;
  --radius-sm: 6px;
  --progress:  #1a7a52;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg:        #111110;
    --surface:   #1c1c1a;
    --border:    #2e2d28;
    --border-md: #3e3d38;
    --text:      #e8e6df;
    --muted:     #9b9890;
    --hint:      #6b6860;
    --green:     #4ecb8a;
    --green-bg:  #0d2a1e;
    --blue:      #6aabf7;
    --blue-bg:   #0d1e35;
    --amber:     #f0b84a;
    --amber-bg:  #271d08;
    --code-bg:   #252420;
    --tag-linux:   #0d2a1e; --tag-linux-t:   #4ecb8a;
    --tag-docker:  #0d1e35; --tag-docker-t:  #6aabf7;
    --tag-web:     #2a120d; --tag-web-t:     #f0836a;
    --tag-git:     #1a1735; --tag-git-t:     #a89df7;
    --tag-monitor: #271d08; --tag-monitor-t: #f0b84a;
  }
}
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 15px;
  line-height: 1.6;
  min-height: 100vh;
}

/* ── Layout ── */
.page { max-width: 780px; margin: 0 auto; padding: 2.5rem 1.25rem 4rem; }

/* ── Header ── */
.site-header { margin-bottom: 2rem; padding-bottom: 1.5rem; border-bottom: 1px solid var(--border); }
.site-header h1 {
  font-size: 22px; font-weight: 600; letter-spacing: -0.3px;
  color: var(--text); margin-bottom: 4px;
}
.site-header .subtitle { font-size: 13px; color: var(--muted); }
.domain-badge {
  display: inline-flex; align-items: center; gap: 6px;
  margin-top: 10px;
  background: var(--blue-bg); border: 1px solid var(--border);
  border-radius: 20px; padding: 3px 10px 3px 8px;
  font-size: 12px; color: var(--blue);
}
.domain-badge .dot {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--blue); opacity: 0.7;
}
.domain-badge code { font-family: 'Menlo', 'Consolas', monospace; font-size: 12px; }

/* ── Progress ── */
.progress-wrap { margin-bottom: 1.75rem; }
.progress-meta { display: flex; justify-content: space-between; align-items: baseline;
  font-size: 12px; color: var(--muted); margin-bottom: 6px; }
.progress-meta strong { color: var(--text); font-weight: 500; }
.progress-track {
  height: 3px; background: var(--border); border-radius: 2px; overflow: hidden;
}
.progress-fill {
  height: 100%; background: var(--progress); border-radius: 2px;
  transition: width 0.35s ease;
}
.reset-btn {
  margin-top: 8px; font-size: 11px; color: var(--hint);
  background: none; border: 1px solid var(--border);
  border-radius: 4px; padding: 3px 8px; cursor: pointer;
}
.reset-btn:hover { color: var(--muted); border-color: var(--border-md); }

/* ── Sections ── */
.section {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  margin-bottom: 10px;
  overflow: hidden;
}
.section-head {
  display: flex; align-items: center; gap: 10px;
  padding: 12px 16px; cursor: pointer;
  user-select: none; -webkit-user-select: none;
}
.section-head:hover { background: var(--bg); }
.section-num {
  width: 26px; height: 26px; border-radius: 50%; flex-shrink: 0;
  display: flex; align-items: center; justify-content: center;
  font-size: 11px; font-weight: 600;
  background: var(--bg); color: var(--hint);
  border: 1px solid var(--border); transition: all 0.2s;
}
.section-num.done { background: var(--green-bg); color: var(--green); border-color: transparent; }
.section-title { flex: 1; font-size: 14px; font-weight: 500; }
.section-count { font-size: 12px; color: var(--hint); margin-right: 4px; }
.chevron { font-size: 9px; color: var(--hint); transition: transform 0.2s; }
.section-head[aria-expanded="true"] .chevron { transform: rotate(180deg); }

.tag {
  display: inline-block; font-size: 10px; font-weight: 500;
  padding: 1px 7px; border-radius: 20px; margin-left: 7px;
  vertical-align: middle; line-height: 18px;
}
.t-linux   { background: var(--tag-linux);   color: var(--tag-linux-t); }
.t-docker  { background: var(--tag-docker);  color: var(--tag-docker-t); }
.t-web     { background: var(--tag-web);     color: var(--tag-web-t); }
.t-git     { background: var(--tag-git);     color: var(--tag-git-t); }
.t-monitor { background: var(--tag-monitor); color: var(--tag-monitor-t); }

/* ── Section body ── */
.section-body { display: none; border-top: 1px solid var(--border); padding: 4px 16px 12px; }
.section-body.open { display: block; }

/* ── Steps ── */
.step { padding: 10px 0; border-bottom: 1px solid var(--border); }
.step:last-child { border-bottom: none; }
.step-label { display: flex; gap: 10px; align-items: flex-start; cursor: pointer; }
.step-label input[type=checkbox] {
  margin-top: 3px; flex-shrink: 0;
  width: 15px; height: 15px; cursor: pointer;
  accent-color: var(--green);
}
.step-body { flex: 1; }
.step-text { font-size: 13.5px; color: var(--text); line-height: 1.5; }
.done-text .step-text { text-decoration: line-through; color: var(--hint); }
.step-note { font-size: 12px; color: var(--muted); margin-top: 3px; line-height: 1.5; }

/* ── Code blocks ── */
pre.cmd {
  background: var(--code-bg); border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 9px 11px; margin: 7px 0;
  font-family: 'Menlo', 'Consolas', 'Courier New', monospace;
  font-size: 11.5px; line-height: 1.65;
  color: var(--text); white-space: pre; overflow-x: auto;
}
pre.cmd .c { color: var(--muted); }

/* ── Callouts ── */
.tip, .warn {
  border-left: 2px solid; border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 7px 10px; margin: 7px 0;
  font-size: 12px; line-height: 1.55;
}
.tip  { background: var(--blue-bg);  border-color: var(--blue);  color: var(--blue); }
.warn { background: var(--amber-bg); border-color: var(--amber); color: var(--amber); }

/* ── Footer ── */
.site-footer {
  margin-top: 2.5rem; padding-top: 1.25rem;
  border-top: 1px solid var(--border);
  font-size: 12px; color: var(--hint);
}